The objective of this investigation is to quantitate the concentrations of estradiol-17 beta (E2) and estrone (E1) in four bovine tissues: muscle, liver, kidney and fat. Steers will be implanted in the ear with 10, 20 or 40 mg of estradiol-17 beta. A fourth group will receive no implant. Six steers will be alloted to each group. Three steers in each group will be killed 30 days after implantation. The remaining three steers in each group will have the implant removed and be killed 24 hours later. Samples of the four tissues will be collected at slaughter and frozen at - 20 degrees C. The tissues will be submitted to a solvent partition procedure and the extracts will be assayed using specific radioimmunoassays for E2-beta and E1. The significance of the experiment will be to determine: (1) if estrogen residues can be detected in edible tissues, (2) whether there is a difference between tissues, (3) whether the level present in tissue is related to dose implanted and (4) whether the level in tissue decreases as a result of a withdrawal period.